Unexpected aliasing

[Bastiaan Veelo]

On Monday, 11 November 2019 at 20:05:11 UTC, Antonio Corbi wrote:
> Defining and using a constructor for WrapIntegerArray seems to 
> work:
>
> void main()
> {
> 	import std.stdio;
>
> 	WrapIntegerArray arr1 = WrapIntegerArray(5);
> 	arr1[0] = 42;
>
> 	WrapIntegerArray arr2 = WrapIntegerArray(5);
>
> 	writeln(arr2[0]); // 42, not 0.
> 	writeln("arr1.wrap.arr.ptr = ", arr1.wrap.arr.ptr);
> 	writeln("arr2.wrap.arr.ptr = ", arr2.wrap.arr.ptr); // 
> identical
> 	assert(arr2[0] == 0); // fails
> }
>
> struct IntegerArray
> {
> 	int[] arr;
> 	alias arr this;
> 	this(int l)
> 	{
> 		arr = new int[l];
> 	}
> }
>
> struct WrapIntegerArray
> {
>         this (int v) {
> 	  wrap = IntegerArray(5);
>         }
>
>         IntegerArray wrap;
> 	alias wrap this;
> }
>
> Hope this helps.
> Antonio

Thanks, Antonio. My problem is that the length of the array 
should be a built-in property of WrapIntegerArray (immutable in 
this case); what I'd actually want is a constructor without 
arguments. Jonathan's suggestion of using a factory function 
comes closest to that.

Bastiaan.